Light signal



E. W. MOORE Aug. 25,1936.

LIGHT SIGNAL Filed Oct. 24, 1931 INVENTOR ATTORNE.Y

908 i M GOO u 3.5 n n: m 5 WW -M 1 m u A m k Patented Aug. 25, 1936PATENT OFFICE I LIGHT SIGNAL Edmund W. Moore, Rochester, N. Y., assignorto General Railway Signal Company, Rochester,

Application October 24, 1931, Serial No. 570,935 5 Claims. (01. 177-329)This invention relates to light signals and more particularly to a meansfor controlling the in-' tensity of such light signals in accordancewith the presence or absence of sunlight and also in ,5- accordance withthe opacity of the atmosphere.

In railway signalling practice, it is found possible to dim the lamps ofcolor light signals when daylight turns to darkness inasmuch as a lessintense light at night displays as distinct 10 an indication as thestronger light during the day time. This practice'has proved desirablefrom the standpoint of reducing glare of such signals at night as wellas saving in energy consumption and increasing the life of the signal [5lamps.

Systems have been devised which employ light sensitive cells controllinga relay which is arranged to apply decreased voltage to such signallamps when this light sensitive cell is not receiving sunlight. However,such systems possess the disadvantage of applying reduced voltage inthe' day time when an abnormal condition of the atmosphere such as f og,smoke or snow obstructs the sun rays from the light sensitive cell, andit 55 is obvious that it is very undesirable to have a lesslntensivelight under such conditions.

In view of the above it is proposed in accordance with this invention toprovide a means for controlling the intensity of illumination of lightsig nals in accordance with the absence of sunlight as well as inaccordance with the clearness of the atmosphere.

Other objects, purposes and characteristic features oi the inventionwill appear as the description thereof progresses during which referencewill be made to the single sheet of drawing which diagrammatically showsthe arrangement of a system for controlling the intensity ofillumination of a pluralityof railway signals in accordo ance with thisinvention.

In the accompanying figure of drawing a section of railroad track TR. isshown as having signals S S and S governing traiiic thereover. Thesesignals are controlled through suitable 5 local means not shown, andenergized by the illustrated signal lighting mains which are in turnenergized by a main lighting transformer T. A relay R is arranged toshift the degree of energization of those mains from the full termo as]voltage of the transformer T- to a reduced voltage tap by its contact I,hence changing the candle power produced by the signal lamps energizedthereby. The relay R is controlled over a circuit including a backcontact 2 of a relay A and 5 a front contact 3 of a relay B.

A photo-electric cell P is arranged in a suitable housing 4 and exposedto the general outside level of light through a glass 5. This cell P isof a well known type which is capable of emitting an amount of currentproportional to the intensity of the light to which it is exposed. Whencurrent is thus emitted from the cell P it is amplified by a suitablemeans such as a conventional vacuum tube amplifying arrangementindicated by a dotted rectangle in the drawing and is then effective toenergize the relay A.

The characteristics of the relay A and its control circuit are selectedso that during normal day time illumination the currentemitted by thecell P is sufiicient to pick up and hold up the armature 2, but isinsufiicient at some lesser degree of illumination such as twilight.Thus, when twilight or darkness reduces the emitted current of thephoto-electric cell P below the operating point of the relay A, itsarmature 2 drops which closes an obvious energizing circuit for therelay R and applies a low degree of energy to the signal lamp mainsthrough its back contact 2.

A second photo-electric cell P is arranged in a housing 6 but isprotected from the direct rays of sunlight by a hood I and receives itslight from a distantly located lamp L equipped with a suitable reflector8. .The current generated in this manner by the cell P is amplifiedthrough a similar associated amplifying unit and is then eflective undernormal clear atmospheric conditions to pick up relay B.

The light from lamp L is of course transmitted through outsideatmosphere and the strength of the lamp L and its distance from the cellP are adjusted so that under normal clear atmospheric conditions, thecurrent emitted by the cell P is Just suflicient to hold up relay B.When some abnormal atmospheric condition exists, such as heavy fog,smoke or snow, which increases the opacity of the atmosphere between thelamp L and the cell P, the light received by the cell P is decreasedsuiliciently to reduce the emitted current below the operating point ofrelay B.

,The' dropping of relay B opens the energizing circuit for the relay Rat front contact 3 and consequently prevents the application of adecreased voltage on the signal lamp'mains even though the absence ofsunlight has conditioned relay A for such an application. It may be herestated that the light from lamp L is of sumcient intensity to preventthe presence or absence of sunlight from producing enough relativechange in the amount of light received by. the cell P to cause aresponse of relay B. The energization of the lamp L may be from anysuitable source but for convenience is shown as the primary 0!transformer T.

The present invention has thus provided a means for automaticallyapplying a high degree of energization to light signals during the daytime when the sunlight requires an intense light to properly displayindications of such signals and has also provided means ior reducingglare at night and conserving power and depreciation o1 lamps byreducing the degree of energization of these lamps during night timewhen a less intense signal light is suflicient. The present inventionhas also provided a means for checking the opacity of the atmospherewhich is arranged to prevent the application of a reduced degree ofenergy to such signal lights at any time when an atmospheric conditionhinders the proper display of indications from such signals.

In describing the present system attention has been directed to onespecific embodiment thereof without attempting to point out the variousalternate or optional features of construction, or the difierentorganizations or combinations that may be employed. For example,photo-electric cells have been shown and described as supplying powerthrough amplifying units to relays A and B but any similar arrangementmay as well be employed such as a light sensitive device in series withan external supply of energy for controlling these relays.

In other words, the particular embodiment of the present invention hasbeen selected to facilitate in the disclosure thereof rather than tolimit the number of forms which it may assume.

Having thus shown and described my invention, what I claim is:--

1. In a circuit voltage regulating means, in

combination, a first relay, an energizing circuit for the relayincluding light sensitive means exposed to atmospheric light, the lightsensitive means being adjusted-for allowing the relay to thus beenergized only during daytime, a second relay, a source of light, alight sensitive means exposed to light from the source after it hastraversed atmosphere, an energizing circuit for the second relay contolled by the last said light sensitive means to e energized only underclear atmospheric conditions, a source of potential, a circuit, thevoltage of which is to be regulated,

the circuit having high and low potential connections to said source,and a voltage control relay having a contact finger and cooperatingfront andback points, for placing high and low voltages, respectively,on the last said circuit through its back and front points; said voltagerelay having an energizing circuit including a back point of said firstrelay, and a front point oi said second relay.

2. In a railway signalling system, in combination, a light signal, asource of electrical energy having a variable potential, means forcontrolling said source to apply a high potential to said signal whenthe atmosphere adjacent said signal is oi a predetermined opacity andfor applying a low potential to said signal when the sunlight adjacentsaid signal is below a predetermined intensity.

3. In a railway signalling system, in combination, a light signal, asource of electrical energy having a variable potential, means forcontrolling said source to apply a high potential to said signal whenthe atmosphere adjacent said signal is of a predetermined opacity andfor applying, subject'to control by the opacity oi the atmosphereadjacent said signal, a low potential to said signal when the sunlightadjacent said signal is below a predetermined intensity.

4. In a railway signalling system, in combination, a light signal, asource of electrical energy having a variable potential, means forcontrolling said source to apply a high potential to said signal whenthe atmosphere adjacent said signal is of a predetermined opacity andfor applying a low potential to said signal when the sunlight adjacentsaid signal is below a predetermined intensity and the atmosphereadjacent the signal is of an opacity below said predetermined opacity.

5. In a railway signalling system, in combination, a light signal, asource 0! electrical energy having a variable potential, means forcontrolling said source to apply a high potential to said signal whenthe atmosphere adjacent said signal is EDMUND W. MOORE. 5

